The present invention relates to an ultrasonic measuring method, an electronic component manufacturing method, and a semiconductor package, and in particular, to an ultrasonic measuring method directed to a measurement object of which a plurality of interfaces cross a direction of ultrasonic radiation, an electronic component manufacturing method for providing, as a product, an electronic component that have been measured and evaluated as being non-defective by the ultrasonic measuring method, and the semiconductor package for use in the ultrasonic measuring method.
Conventional apparatuses for measuring the interiors of objects include an ultrasonic measuring apparatus that performs measurement by means of ultrasonic waves emitted and reflected back from an internal portion of an object (see, e.g., Patent Document 1 (Japanese Unexamined Patent Publication No. 05-333007) and Patent Document 2 (Japanese Unexamined Patent Publication No. 06-294779)).
As a conventional ultrasonic measuring apparatus, an ultrasonic measuring apparatus for measuring the interior of a semiconductor package is described.
FIG. 11 is a schematic structural view of a conventional ultrasonic measuring method. X-, Y-, and Z-axes are indicated in the figures for clarifying the relative positional relationships among the figures.
In FIG. 11, an ultrasonic measuring apparatus 1 includes an ultrasonic probe 2 for emitting and receiving ultrasonic waves, an input unit 3 for inputting conditions for ultrasonic measurement, such as frequencies of ultrasonic waves to be transmitted, a control unit 4 for processing information acquired from the ultrasonic probe 2 and the input unit 3 to control the operation of the ultrasonic probe 2, and a display unit 5 for displaying results of measurement including ultrasonic waveforms.
The operation of the ultrasonic measuring apparatus 1 is briefly described.
Based on the conditions for measurement inputted at the input unit 3, ultrasonic waves that are emitted with the movement of the ultrasonic probe 2 controlled at the control unit 4 are applied onto a semiconductor package 7 through the medium of water 6 in a container. The reflected waves reflected back from the semiconductor package 7 serving as a measurement object are received at the ultrasonic probe 2. The received reflected waves are processed at the control unit 4 such that the semiconductor package 7 is determined whether it is defective or not and an image thereof is created, and the result is displayed at the display unit 5.
The ultrasonic probe 2 is used here both for emission and reception. The control unit 4 includes a pulser/receiver that converts the reflected waves received at the ultrasonic probe 2 into voltages for amplification, as well as an image processor that visualizes intensity values of the voltage waveforms.
The semiconductor package 7 is a package which has a multilayer structure along the direction of ultrasonic radiation (the Z-axis direction in FIG. 11) including a plurality of interfaces.
To describe the conventional ultrasonic measurement in further detail, the measuring part and areas therearound in FIG. 11 are enlarged and described along with the structure of the semiconductor package 7.
FIG. 12 is a schematic view of the conventional ultrasonic measurement.
In FIG. 12, the semiconductor package 7 includes a substrate 8 having substrate-side electrodes on its upper surface, solders 9 serving as examples of bonding members provided between the substrate 8 and the respective substrate-side electrodes, an interposer 10 having interposer-side electrodes bonded by the solders 9 to the substrate-side electrodes on the substrate 8, a semiconductor chip 11, lead wires 12 connecting the interposer 10 with the semiconductor chip 11, and a resin mold 13 covering the semiconductor chip 11.
As shown in FIG. 12, the semiconductor package 7 is sunk in water in the example shown here, wherein the semiconductor package 7 placed in a liquid (water) 6, which package serves as a specific example of a measurement object, has a plurality of interfaces formed therein, including an interface between the water 6 and the resin mold 13, an interface between the resin mold 13 and the interposer 10, and an interface between the interposer 10 and the solder 11.
In this structure, the ultrasonic waves from the ultrasonic probe 2 are applied onto the semiconductor package 7, and when the reflected waves back from the semiconductor package 7 are received at the ultrasonic probe 2, the signals thereof have a waveform in which a plurality of waves are overlapped with one another. The waveform is described.
In the case where the semiconductor package 7 with a plurality of interfaces as shown in FIG. 12 is subjected to ultrasonic measurement, a waveform shown in FIG. 13 is acquired.
FIG. 13 is a view illustrating an ultrasonic waveform acquired in the conventional ultrasonic measurement. A description is given on a method for determining defectiveness or non-defectiveness at a measurement location using the waveform.
As shown in FIG. 13, in the case where the semiconductor package 7 having a plurality of interfaces therein is measured, it is difficult to define a measurement location (interface) because a plurality of waves are overlapped with one another.
Hence, with a surface of the semiconductor package 7 that gives stable ultrasonic waveforms being set as a reference, a measurement location (interface) is defined by using time-delay (phase shifting) from the surface.
In FIG. 13, a trigger 14 (at time t0) is provided on the time base with respect to surface waves from the surface of the semiconductor package 7. Subsequently, based on the internal structure of the semiconductor package 7, a time domain called a gate 15 (at time t1) is set with the trigger 14 placed at a zero origin, with respect to the reflected waves at a measurement location. Then, comparison with a threshold value is made within the section (the time domain) of the gate 15 to evaluate the measurement location.
The method however entails an issue of degradation in accuracy of measurement in the case where serial ultrasonic measurement is performed on two semiconductor packages of the same kind. The issue is described.
FIG. 14 is a view illustrating waveforms of reflected ultrasonic waves acquired in the conventional ultrasonic measurement.
When two semiconductor packages of the same kind are subjected to serial ultrasonic measurement, waveforms shown in FIG. 14 are acquired. As shown in FIG. 14, the reflected waves from the two semiconductor packages, i.e., a reflected wave 16 from a first semiconductor package and a reflected wave 17 from a second semiconductor package, are acquired shifted on the time base.
According to the conventional ultrasonic measurement, a measurement location of the reflected wave 17 is evaluated by using a trigger 18 (at time t2) and a gate 19 (at time t3) that are set initially based on the reflected wave 16. Thus, as shown in FIG. 14, the gate 19 (at time t3) deviates widely from the true measurement location (at time t4) of the reflected wave 17.